<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>04.外边距</title>
    <style>
        .box {
            /* margin-top: 100px;
            margin-bottom: 100px;
            margin-left: 50px;
            margin-right: 50px; */
            margin: 100px;
            margin: 100px 20px;
        }
    </style>
</head>
<body>
    <div style="background-color: red;">上</div>
    <input type="text"><input class="box" type="button" value="外边距测试"><input type="text">
    
    
    <div style="background-color: red;">下</div>
    
</body>
</html>